Insatiable thirst: Managing polydipsia

Julia Perch, MD andKevin M. O’Connor, MDDr. Perch is a resident and Dr. O’Connor is associate professor and clinical director of psychosomatic medicine, department of psychiatry, University of Medicine and Dentistry of New Jersey, Newark.

Assess for psychiatric symptoms such as anxiety or delusional beliefs that might contribute to your patient’s water consumpton

Psychogenic polydipsia (PPD) is a chronic, relapsing, and potentially life-threatening disorder characterized by compulsive consumption of large quantities of water resulting in “delutional hyponatremia.” PPD occurs in 6% to 20% of psychiatric patients, most often with schizophrenia.1

In most patients with PPD, an electrolyte disturbance remains asymptomatic. However, superimposed and sudden ingestion of 3 to 4 liters of water can rapidly further dilute plasma and overwhelm the body’s compensatory reserves, leading to brain edema, seizures, coma, and even death.

The following prevention and treatment strategies might reduce morbidity and mortality in hospitalized patients diagnosed with PPD and lessen the cost of treating this serious illness.

Develop rapport. Understand that your patient has little control over his or her compulsive water intake. Remain nonjudgmental to help gain your patient’s trust.

Encourage communication among treatment team members. PPD patients are notoriously creative in sneaking water from unexpected places such as toilets and shower rooms. Staff vigilance is required to detect and prevent such clandestine behaviors.

Consult with an internist when necessary, especially if your patient has a comorbid cardiac condition that requires a low-sodium diet and/or diuretics.

Review psychotropic medications. In case reports of schizophrenia patients with PPD, switching from a typical to an atypical antipsychotic has shown efficacy in treating PPD.2

Restricting fluids to 2 to 3 liters a day combined with “a token economy”—a method of positive reinforcement to increase desired behavior—has been used to successfully treat the disorder.2

Monitor adherence by weighing patients twice a day and checking serum sodium levels frequently. Normal water retention is cyclic and peaks in the early afternoon; therefore, early-morning screening for hyponatremia may not accurately reflect the severity of water abuse. A diurnal weight gain of ≥0.6% is unusual and might point to PPD.2